Poor inhibitory control is associated with greater stimulation and less sedation following alcohol

A randomized trial of the effects of COMT inhibition on subjective response to alcohol: Moderation by baseline COMT activity and mediation of alcohol self-administration

BACKGROUND

Poor inhibitory control and enhanced subjective response to alcohol are interrelated risk factors for alcohol use disorder (AUD) that share underlying neural substrates, including dopamine signaling in the right prefrontal cortex, a potential target for pharmacological intervention. Cortical dopamine inactivation is primarily regulated by catechol-O-methyltransferase (COMT), an enzyme with large variation in activity as a function of the COMT rs4680 (val158met) single nucleotide polymorphism. In a previous randomized, placebo-controlled trial of the COMT inhibitor tolcapone (200 mg TID) in non-treatment-seeking participants with AUD, we found that tolcapone, relative to placebo, reduced alcohol self-administration only among rs4680 val-allele homozygotes, whose COMT activity is higher than in met-allele carriers.

METHODS

We conducted secondary analyses of the effects of tolcapone and baseline COMT activity, as indexed by both rs4680 genotype and an enzymatic activity assay, on the subjective response to alcohol in a bar-laboratory paradigm among 60 participants in the previous trial.

RESULTS

Tolcapone did not affect alcohol-induced stimulation or sedation more than placebo. However, baseline COMT activity moderated the effects of the drug on both outcomes, such that tolcapone-treated participants with higher baseline COMT activity had less stimulation (p = 0.008) and sedation (p = 0.053) than participants with lower baseline COMT activity and those treated with placebo. Additionally, alcohol-induced stimulation significantly mediated the interacting effects of baseline COMT activity and tolcapone on bar-laboratory self-administration.

CONCLUSIONS

Tolcapone may reduce subjective response to alcohol more effectively among individuals with preexisting high COMT activity an effect that could account for the drug's reduction of alcohol consumption among these individuals.

Change in brain asymmetry reflects level of acute alcohol intoxication and impacts on inhibitory control

Alcohol is one of the most commonly used substances and frequently abused, yet little is known about the neural underpinnings driving variability in inhibitory control performance after ingesting alcohol. This study was a single-blind, placebo-controlled, randomized design with participants (N = 48 healthy, social drinkers) completing three study visits. At each visit participants received one of three alcohol doses; namely, a placebo dose [equivalent Blood Alcohol Concentration (BAC) = 0.00%], a low dose of alcohol (target BAC = 0.04%), or a moderate dose of alcohol (target BAC = 0.08%). To measure inhibitory control, participants completed a Go/No-go task paradigm twice during each study visit, once immediately before dosing and once after, while their brain activity was measured with time-domain functional near-infrared spectroscopy (TD-fNIRS). BAC and subjective effects of alcohol were also assessed. We report decreased behavioral performance for the moderate dose of alcohol, but not the low or placebo doses. We observed right lateralized inhibitory prefrontal activity during go-no-go blocks, consistent with prior literature. Using standard and novel metrics of lateralization, we were able to significantly differentiate between all doses. Lastly, we demonstrate that these metrics are not only related to behavioral performance during inhibitory control, but also provide complementary information to the legal gold standard of intoxication (i.e. BAC).

Differential effects of UPPS-P impulsivity on subjective alcohol response and craving: An experimental test of acquired preparedness

Recent studies have extended the acquired preparedness model to experimental data, finding that impulsivity predicts subjective alcohol response, a related yet distinct construct from expectancies. However, studies have not tested whether specific facets of impulsivity predict subjective response, or whether impulsivity indirectly predicts alcohol craving through subjective response. Young adults who reported past-month binge drinking (N = 448) participated in a placebo-controlled alcohol administration study. Mediation models tested whether UPPS-P impulsivity facets indirectly predicted alcohol craving through subjective response on the ascending and descending limbs of the blood alcohol content (BAC). High arousal positive (e.g., sociable), low arousal positive (e.g., relaxed), high arousal negative (e.g., rude), and low arousal negative (e.g., dizzy) subjective effects were measured across limbs. Moderation by beverage condition was not detected, so models were collapsed across beverage condition. Sensation seeking indirectly predicted craving through high arousal positive subjective response on both limbs, whereas positive and negative urgency directly predicted craving. When controlling for baseline subjective response and craving, effects of sensation seeking and negative urgency on subjective response and craving became nonsignificant. The effects of positive urgency on craving remained, and an effect of positive urgency on high arousal positive effects emerged on the ascending limb. Findings suggest that relations among impulsivity, subjective response, and craving are contingent upon the specific facet of impulsivity. Interventions targeting predrink cue exposure and/or positive emotionality may be most effective for sensation seekers, whereas targeting subjective response and/or expectancies may be most efficacious for individuals high in positive urgency. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Moderators of subjective response to alcohol in the human laboratory

BACKGROUND

Subjective response (SR) to alcohol represents a biobehavioral risk factor for heavy drinking and for developing alcohol use disorder (AUD). Identifying moderators of SR have been hindered by small sample sizes that are often used in alcohol administration studies.

METHODS

This study combined data from multiple alcohol administration trials to test whether sex, family history of alcohol problems, and impulsivity (via delay discounting) predict SR to alcohol, comprised of four domains: stimulation, sedation, negative affect, and craving. Non-treatment-seeking heavy drinkers (N = 250) completed a battery of self-report scales and behavioral measures of alcohol use and problems, mood, and impulsivity. All participants completed an intravenous alcohol administration session wherein SR domains were measured at baseline, 20, 40, and 60 mg%.

RESULTS

Analyses using multilevel modeling showed that male sex independently predicted higher alcohol-induced stimulation and alcohol craving, after controlling for other moderators. A family history of alcohol problems also independently predicted alcohol craving after controlling for other moderators.

CONCLUSIONS

Using a large sample and advanced data analytic methods, this study extends the literature on alcohol administration by identifying important moderators of SR in heavy drinkers: namely, male sex and family history of alcohol problems. These findings consolidate and extend a growing body of research aimed at differentiating individuals most likely to report the SR features that confer risk for AUD.

Neural correlates of inhibitory control are associated with stimulant-like effects of alcohol

Poor inhibitory control and heightened feelings of stimulation after alcohol are two well-established risk factors for alcohol use disorder (AUD). Although these risk factors have traditionally been viewed as orthogonal, recent evidence suggests that the two are related and may share common neurobiological mechanisms. Here we examined the degree to which neural activity during inhibition was associated with subjective reports of stimulation following alcohol. To assess neural changes during inhibition, moderate alcohol drinkers performed a stop signal task during fMRI without drug. To assess subjective responses to alcohol they ingested alcohol (0.8 g/kg) or placebo beverages under double-blind conditions and provided subjective reports of stimulation and sedation. Feelings of stimulation following alcohol were inversely associated with activity in the supplementary motor area, insula, and middle frontal gyrus during inhibition (successful stop trials compared to go trials). Feelings of sedation did not correlate with brain activation. These results extend previous findings suggesting that poor inhibitory control is associated with more positive subjective responses to alcohol. These interrelated risk factors may contribute to susceptibility to future excessive alcohol use, and ultimately lead to neurobiological targets to prevent or treat AUD.

Electrocortical correlates of impaired motor inhibition and outcome processing are related in high binge-watching

Models posit problematic binge-watching to involve a vicious circle of low motivation for alternative activities, low sensitivity for the consequences of neglected goals, and low self-control. As such, simultaneously impaired feedback and inhibitory functioning might contribute to binge-watching. We tested the hypothesis that blunted feedback-related brain activity is coupled with attenuated inhibitory brain activity in binge-watchers. High (n = 32) and non-binge-watchers (n = 31) performed go/nogo (inhibition) and stop signal (stopping) tasks and a flanker paradigm with performance feedback during electroencephalography. We examined how neural correlates of inhibition and stopping were associated with outcome processing in each group. We assessed the temporospatial relationship using a single-trial regression approach. High binge-watchers, but not non-binge-watchers, who differentiated less between gains and losses at the neural level (feedback-P3b) also recruited less brain activity during both inhibition and stopping (inhibition-P3 and stopping-P3). Exploratory analyses suggested that these relationships were most prominent in high binge-watchers with high loss of control over watching. Main effects of the group in performance or EEG did not emerge. These results suggest a potentially problematic interaction between outcome and inhibitory functions in binge-watchers. Insensitivity to behavioral consequences along with inhibitory impairments may also confer a long-term risk for compulsive watching. Our multi-modal approach may be particularly suited to detect such an underlying risk marker.

Striatal activation to monetary reward is associated with alcohol reward sensitivity

One well-known phenotypic risk factor for the development of alcohol use disorder is sensitivity to the rewarding effects of alcohol. In the present study, we examined whether individuals who are sensitive to alcohol reward are also sensitive to nondrug rewards, thereby reflecting a broader individual difference risk factor. Specifically, we tested the hypothesis that subjective response to acute rewarding effects of alcohol would be related to neural activation during monetary reward receipt relative to loss (in the absence of alcohol). Community-recruited healthy young social drinkers (N = 58) completed four laboratory sessions in which they received alcohol (0.8 g/kg) and placebo in alternating order under double-blind conditions, providing self-report measures of subjective response to alcohol at regular intervals. At a separate visit 1-3 weeks later, they completed a reward-guessing game, the 'Doors' task, during fMRI in a drug-free state. Participants who reported greater motivation (i.e., wanting) to consume more alcohol after a single moderate dose of alcohol also exhibited greater neural activation in the bilateral ventral caudate and the nucleus accumbens during reward receipt relative to loss. Striatal activation was not related to other subjective ratings including alcohol-induced sedation, stimulation, or pleasure (i.e., feeling, liking). Our study is the first to show that measures of alcohol reward are related to neural indices of monetary reward in humans. These results support growing evidence that individual differences in responses to drug and nondrug reward are linked and together form a risk profile for drug use or abuse, particularly in young adults.

Stability of acute responses to drugs in humans across repeated testing: Findings with alcohol and amphetamine

BACKGROUND

Controlled drug challenge studies provide valuable information about the acute behavioral effects of drugs, including individual differences that may affect risk for abuse. One question that arises in such studies is whether a single administration of a drug (and placebo) provides an accurate measure of response to the drug.

METHODS

Here, we examined data from two studies, one with alcohol and one with amphetamine, in which participants received two administrations of the drug and placebo. In this analysis we assess the stability of acute subjective and cardiovascular responses to the drugs across the two administrations. We examine i) systematic increases or decreases to the drugs from the first to the second administration, ii) test-retest reliability within individuals and iii) the accuracy of the acute drug responses to predict drug choice in a later session.

RESULTS

Responses were largely stable across sessions, although on the second session amphetamine "liking" was higher, and subjective responses to placebo including "liking" and "want more" decreased in both studies. Test-retest reliability within individuals was high. Responses during the first drug administration were as accurate in predicting drug choice as responses during both administrations combined.

CONCLUSIONS

Our findings indicate that a single administration of drug (and placebo) provides a good index of an individual's responses to alcohol or amphetamine, when participants are tested under controlled experimental conditions.